Reactivity and the mechanisms of reactions of beta-sultams with nucleophiles

摘要

Ethane-1,2-sultam has a pK(a) of 12.12 +/- 0.06 at 30 degreesC and its rate of alkaline hydrolysis shows a pH-dependence reflecting this so that the observed pseudo first-order rate constant at pHs above the pK(a) are pH independent. There is no evidence of neighbouring group participation in the hydrolysis of either N-alpha-carboxybenzylethane-1,2-sultam or N-(hydroxyaminocarbonylmethyl)-2-benzylethane-1,2-sultam. Oxyanions, but not amines or thiols, react with N-benzoylethane-1,2-sultam in water by a nucleophilic ring opening reaction confirmed by product analysis and kinetic solvent isotope effects. A Bronsted plot for this reaction has two distinct correlations with beta(nuc) = 0.52 and 0.65 for weak and strong bases, respectively, although a statistically corrected plot may indicate a single correlation. [References: 62]